Monitor Description

WARNING: This page is about a different car, the 2025 Lexus NX 250, 2024 Lexus NX 250, 2023 Lexus NX 250, and 2022 Lexus NX 250. However, it is still accessible from the selected car via links, so may be relevant.

except Mexico Models

P0400-00
During fuel cut (vehicle being driven with idle ON), when the change in intake manifold pressure when the EGR valve assembly is operating and not operating is insufficient, the ECM determines that the EGR valve is stuck and stores DTC P0400-00 and illuminates the MIL.
P0401-9C
During fuel cut (vehicle being driven with idle ON), when the change in intake manifold pressure when the EGR valve assembly is operating and not operating is insufficient, the intake manifold pressure is less than the threshold when the EGR valve assembly is not operating, the ECM determines that the flow through the EGR valve is hindered and stores DTC P0401-9C and illuminates the MIL.
P0402-9B
During fuel cut (vehicle being driven with idle ON), when the change in intake manifold pressure when the EGR valve assembly is operating and not operating is insufficient, the intake manifold pressure is more than the threshold when the EGR valve assembly is not operating, the ECM determines that the flow through the EGR valve is excessive and stores DTC P0402-9B and illuminates the MIL.

for Mexico Models

P0401-9C
The ECM monitors the pressure inside the intake manifold while opening and closing the EGR valve during fuel cut operation. If there is no change in the manifold absolute pressure sensor value, the ECM interprets this as a malfunction of the EGR valve assembly, illuminates the MIL and stores this DTC.